Lithium batteries have lately attracted attention as high energy density batteries, and, therefore, it is possible to miniaturize and to lighten the weight of batteries.
LiCoO.sub.2, LiNiO.sub.2 and LiMn.sub.2 O.sub.4 are well known as a positive electrode material for a lithium battery. Lithium alloys and carbon materials are well known as a negative electrode material for lithium secondary batteries.
In the field of this kind of secondary batteries, it has been tried to develop higher voltage batteries or higher output power density batteries. A 4V class battery using LiCoO.sub.2 and carbon material for a positive and a negative electrode, respectively, has been introduced in the market.
Japanese Patent publication (Laid-Open) Hei 8-180875 discloses a high output power density lithium secondary battery, 4.5V class of discharge voltage, comprising a positive electrode having Li.sub.x Ti.sub.y O.sub.4 (in which 0&lt;x.ltoreq.2 and 1&lt;y.ltoreq.3) or Li.sub.a Ti.sub.b M.sub.c O.sub.4 (in which 0&lt;a.ltoreq.2, 1&lt;b.ltoreq.3 and 0&lt;c.ltoreq.3, and M is at least one element selected from the group consisting of Mn, Fe, Cr, Ni, Co, Mg and B), and a negative electrode containing lithium metal, lithium alloy or carbon material.
On the other hand, however, development has also been conducted of lower voltage driving type batteries to reduce uptake electric power of IC. It is required to develop a lithium secondary batteries having lower discharge voltage as a driving electric source for the IC.
The present invention has been completed to satisfy such requirements. An object of the present invention is to provide a lithium secondary battery having about 1.5 V of discharge voltage and being preferable as a driving electric source for a low voltage driving type IC and the like.